a) Field of the Invention
The present invention relates to a golf club with a head made of a plurality of separate shells, having a shaft connected thereto.
b) Description of the Background Art
Conventionally, in order to produce wood golf club heads or so-called xe2x80x9cmetal Woodxe2x80x9d, it is known art to join a plurality of metallic shells together. In those types of heads, respective peripheries of plural metallic shells are integrally welded to one another.
As golf club heads are progressively large-sized, with lower centers of gravity thereof being pursued, respective separate shells for constructing a head also are getting thinner and thinner. For example, in the case that a beta titanium alloy is used, face is normally as thin as 2.5 to 3.0 mm, sole and crown are each as thin as 1 mm or below. When welding such thin separate shell together, there occurs a problem that heat by the welding causes deformation. More specifically, when welding a crown to a face, a front edge of the crown is likely to sink toward the inside. In that case, excessive grinding would be needed as a post-processing to obtain a predetermined configuration, so that the resultant thickness of welded portions becomes too small. As time of striking balls, resulting to a likelihood to cause cracks therein.
On the other hand, whilst the peripheral edges of a plurality of metallic shells are welded together in metal wood golf clubs, welding is performed by abutting the adjacent peripheral edges to one another, so that there is another problem that an excessive amount of welding bead enters inside. Whilst welding bead is to be heaped up in an approximately even manner along the welding advancing direction, if a portion of the welding bead sinks into the inside, then the portion is depressed, and thus another welding bead must be heaped up again. If beads are repeatedly heaped up this way, more welding heat is applied due to the welding, so that the undesirable deformation is more likely to occur. On the other hand, if the excessive welding bead is heaped, then it would be difficult to visually confirm the configuration of parts where respective shells are joined. Further, there would occur a further problem that the applied heat causes a change in strength property of titanium alloy material so that the fragility is increased, thus leading to the possible destruction of the neighborhood of the parts to be welded. Even though non-solution treatment material is used, yet the welding bead is likely to cause deformation to some extent.
Whereas, in paragraphs 0008 to 00010 in Japanese Un-Examined patent publication No 11-114106 is disclosed a method for manufacturing a golf club, wherein in a golf club head comprising a hollow metallic body shell and a face shell joined to an opening of said body shell which is open to the face shell, at least one of an end face of the opening of the body shell or an edge of the face shell is formed with a plurality of projections to be abutted to the other, while beads 15 are buried in recesses formed between the projections, to fix the face shell to the opening of the body shell; and also a method for manufacturing a golf club wherein a welding member is heated while being abutted to the recesses formed between the above projections when abutting the face shell to the head body, so that the welding member is fused to be filled in said recesses, to thereby fix the face shell to the opening of the head body. The prior art teaches that such methods ensure beads to be properly positioned in the recesses between the projections in a position where the body shell and the face shell are joined, without overlapping with the body shell or the face shell, so that the face shell is lightened.
According to the prior art, however, there still remains a problem that when joining respective thin separate shells together by welding, they are deformed due to the heat in welding. Further, the prior art involves a further problem that as one of the members to be abutted is provided with projections, and beads are buried in recesses formed between the projections, excessive amount of welding bead is likely to enter the inside through the recesses.
Further, U.S. Pat. No. 5,482,279 to Antonious discloses a thickened peripheral portion (reinforcing portion) 30, but the prior art fails to disclose anything about the attachment structure associated with the welding of a crown shell. U.S. Pat. No. 5,584,770 to Jensen discloses in its FIG. 30 the provision of a specific skirt 60, and U.S. Pat. No. 5,292,129 to Long et al. also discloses in its FIG. 5 a rib element 42, each of which however only discloses a face shell and a crown shell formed integrally with each other in advance. Therefore, the prior art involves no technical teachings about the attachment structure associated with the welding of the face shell and the crown shell.
Whereas U.S. Pat. No. 5,704,850 to Shieh discloses that a top cover plate 2 is provided with the front projecting blocks 5, while a solder E being provided with the blocks 5 being abutted to the face panel 41. It is to be noted that the distal ends of the blocks 5 are substantially flush with the distal end of the plate 2, with the respective distal ends being abutted to the rear surface of the panel 41, with a solder E being provided in gaps S. According to such golf club head, however, whilst the plate 2 is fixed to the panel 41 in the gaps S, using a solder E, the distal end of the plate 2 itself is only abutted to the rear surface of the panel 41 in other portions than the gaps S, and thus there remains a problem that such structure is unlikely to ensure a sufficient connection strength to withstand the impact caused when a golf ball is struck on the panel 41.
U.S. Pat. No. 6,238,300 to Igarashi discloses that the distal end of the top plate 54 is joined to the upper end of the face plate 56, using a weld bead 64, with the plate portion 52C being disposed on a rear of the face plate 56. According to the prior art, however, the same problem as that of the above-mentioned U.S. Pat. No. 5,704,850 would occur as the plate 54 and the plate 56 the plate 54 and the plate portion 52C are abutted to each other so as to be welded with the weld bead.
Referring o FIG. 7 of U.S. Pat. No. 6,299,549 to Shieh, the head body 10 is provided with the rim 13, and the face plate 20 is provided, as illustrated. According to the structure shown in FIG. 7, yet the tip end of the upper surface of the head body 10 is abutted to the face plate 20, so that the same problem as that of the above-mentioned U.S. Pat. No. 5,704,850 would occur.
Also referring to FIG. 4 of U.S. Pat. No. 5,993,329 to Shieh, the casing 10 is fixed to the lace plate 30 through the coupling block 20, However, the prior art involves no technical teachings about the attachment structure associated with the welding of the face shell and the crown shell in a golf club head made up of a plurality of shells.
Also, it is noted that the blocks 213 disclosed in U.S. Pat. No. 5,709,615 to Liang are positioning elements provided on an edge of the face plate 21. The prior art also involves no technical teachings about the attachment structure associated with the welding of the face shell and the crown shell in a golf club head made up of a plurality of shells.
Referring to U.S. Pat. No. 4,438,931 to Motomiya, the prior art discloses a head constructed of three different shells that are joined together with the respective shells being abutted to one another. The prior art, however, only discloses background art on which the present invention is based, failing to disclose an improved attachment structure associated with the welding of the face shell and the crown shell in this type of a golf club head.
Still further, U.S. Pat. No. 4,465,221 to Schmidt discloses that the sole plate 12 is fixed to the opening 21, but the prior art does not involve any technical teachings about the attachment structure associated with the welding of the face shell and the crown shell in the above-mentioned type of a golf club head. Neither U.S. Pat. No. 5,261,664 to Anderson disclosing the plate 21 fixed to the body portion 20 using the fasteners 24-27 nor U.S. Pat. No. 5,271,621 to Lo disclosing the projection unit 43 that is similar to the thickened peripheral portion 30 of U.S. Pat. No. 5,482,279 to Antonious.
To eliminate the above problems, it is, therefore, a main object of the present invention to provide a golf club having a head constructed by joining a plurality of metallic shells, and a shaft connected to the head, wherein said head is less likely to be deformed by the heat in welding.
It is another object of the present invention to provide a golf club having a head constructed by joining a plurality of metallic shells, wherein said head is protected from the excessive welding beads entering the inside and excessive heat being applied thereto.
To attain the above objects, there is provided, in accordance with a first aspect of the invention, a golf club, which comprises: a head formed by joining a plurality of separate shells one another, said separate shells including a face shell having an upper edge and a crown shell having a front edge; a shaft connected to said head; a plurality of projections provided on the front edge of said crown shell, each of said projections being laterally spaced from each other, protruding from said front edge by a first projection length that is equal to or slightly less than a thickness of the upper edge of said face shell so that each projection is anchored in such a manner that rests on the upper edge of said face shell, and a reinforcing member provided along the front edge of said crown shell, said reinforcing member being integrally fixed to an inside of the front edge of said crown shell, and protruding from the front edge of said crown shell by a second projection length that is less than said first length so that a distal end of said reinforcing member is positioned on a rear of said face shell, wherein bead is placed between the upper edge of said face shell and the front edge of said crown shell so that welding is performed to weld said separate shells together.
Thus, the front edge of the crown shell is reinforced by the reinforcing member, so that the thermal deformation of the front edge at the time of welding can be prevented, well withstanding such thermal deformation tendency. Further, as welding is performed with the projections being anchored in such a manner that rest on the upper edge of the face shell, the upper edge of the face shell can be welded to the front edge of the crown shell as originally designed, without allowing the front edge from sinking in the inside of the head due to the thermal deformation caused by the welding heat. Furthermore, as the front edge of the reinforcing member that protrude from the front edge of the crown shell is positioned on a rear face of the face shell so as to form the narrow clearance between the right and left reinforcing members, not only can the sinking of the weld bead be reduced but can the better beads be formed.
According to a second aspect of the invention, there is provided a golf club comprising: a head formed by joining a plurality of separate shells one another, said separate shells including a face shell having an upper edge, said upper edge being formed with a flat portion on a front side and a recess on a rear side, and a crown shell having a front edge; a shaft connected to said head; a plurality of projections provided on the front edge of said crown shell, each of said projections being laterally spaced from each other, protruding from said front edge so that each projection is anchored in such a manner that rests on the flat portion of said upper edge of said face shell, and a reinforcing member provided along the front edge of said crown shell, said reinforcing member being integrally fixed to an inside of the front edge of said crown shell, having a distal end positioned rearwardly of said face shell, wherein bead is placed between the upper edge of said face shell and the front edge of said crown shell so that welding is performed to weld said separate shells together.
The structure thus made is particularly advantageous in that better forming of the weld bead is achieved by providing the recess on a rear side of the upper edge of the face shell.
According to a further aspect of the invention, there is provided a golf club set forth in the second aspect, in which said projections, the front edge portion of said reinforcing members and the upper edge of said face shell are integrally welded to one another.
According to the structure, the crown shell can be integrally joined to the face shell through the reinforcing member, thus enhancing connection strength therebetween. Further, a strong and good weld bead can be provided through a single weld stroke.